Detection of helical water flows in sub-nanometer channels

P Zelenovskii and M Soares and C Bornes and I Marin-Montesinos and M Sardo and S Kopyl and A Kholkin and L Mafra and F Figueiredo, NATURE COMMUNICATIONS, 15, 5516 (2024).

DOI: 10.1038/s41467-024-49878-7

Nanoscale flows of liquids can be revealed in various biological processes and underlie a wide range of nanofluidic applications. Though the integral characteristics of these systems, such as permeability and effective diffusion coefficient, can be measured in experiments, the behaviour of the flows within nanochannels is still a matter of speculation. Herein, we used a combination of quadrupolar solid-state NMR spectroscopy, computer simulation, and dynamic vapour sorption measurements to analyse water diffusion inside peptide nanochannels. We detected a helical water flow coexisting with a conventional axial flow that are independent of each other, immiscible, and associated with diffusion coefficients that may differ up to 3 orders of magnitude. The trajectory of the helical flow is dictated by the screw-like distribution of ionic groups within the channel walls, while its flux is governed by external water vapour pressure. Similar flows may occur in other types of nanochannels containing helicoidally distributed ionic groups and be exploited in various nanofluidic lab-on-a-chip devices. Nanoscale liquid flows are crucial in biological processes and nanofluidic applications but remain theoretically challenging within nanochannels. Authors utilize advanced techniques to uncover independent, immiscible helical, and axial water flows in peptide nanochannels, with implications for nanofluidic devices.

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